1. Field of the Invention
The present invention relates generally to trenching machines. In particular, the present invention is directed to a mount for removably mounting a trencher attachment to a power unit, and to a method for using the mount.
2. Description of the Prior Art
A variety of different types of trenchers including walk-behind, walk-beside and riding units are in widespread use. Extensive trenching operations and those carried out in tough soil conditions are often performed using riding trenchers. Trenchers of this type generally have a trenching attachment which is removably mounted to a power unit.
Models T135 and T136 BOBCAT trenchers manufactured and sold by the Melroe Company of Fargo, N. Dak. are fully hydrostatic machines. Separate trenching attachments mounted at different locations on the back of the power unit are used for centerline and offset trenching with the BOBCAT trenchers. In the center position, the trenching chain extends rearwardly from the center of the power unit. In the offset position the trenching chain extends rearwardly from the center of the power unit tires. It is therefore not possible to trench directly adjacent a structure. The trenching attachment itself is heavy and awkward, requiring the use of a lift mechanism to position the attachment with respect to the power unit so that it can be bolted on. These procedures are inefficient and time-consuming.
Still other known trencher designs such as the DlTCH WlTCH Models 2300 and 4010 have a head drive with two sprockets, one positioned for centerline trenching, and the other positioned for offset trenching. The trenching boom can be moved to either position. It is, however, a time-consuming process to move the boom.
Hook and eye attachment mounting systems are generally known and disclosed, for example, in the VME Americas Inc. ad on pp 60-61 of the Aug. 15, 1988 issue of Construction Equipment, and the Bauer U.S. Pat. No. 3,732,996. These mounting systems include a pair of laterally or transversely spaced hooks mounted to the attachment above or below a corresponding pair of laterally spaced eyes. The hooks are engaged with corresponding bar members on the loader, while slidably mounted pins on the loader engage the eyes of the attachment. A pair of hydraulic cylinders are sometimes used to extend and retract the mounting pins with respect to the eyes. It is also known to mount the hooks and eyes to the loader, and have the bars and pins on the attachment.
There is a continuing need for improved trencher mounting systems. These systems should be versatile and convenient to use.